I was looking at a simple niacinamide serum (3%), and was told that if acids, such as AHAs, L-Ascorbic Acid, etc., are uses simultaneously, it will cause facial flushing.

It was advised that the acid product should be applied first, then wait 30 minutes for the skin to return to its "normal" pH, and then apply the niacinamide product.

It seems that if niacinamide and an acid are combined, the acid will hydrolyze the niacinamide and convert it to niacin, which will then result in a facial flush.

Does an acid really hydrolyze niacinamide?

Is the waiting time of 30 minutes too much, or can one wait just 10-15 minutes, if facial flushing is an issue?

Nia24 is a brand of products that contains 5% niacin, and I have not read in their literature that one must use acid products either separately, or during different times of the day, or that there is an increased risk of facial flushing if used simultaneously with acids.

Indeed, acid environment may cause some degree of niacinamide hydrolysis. However, it is hard to say w/o a test whether the rate of production and penetration of the resulting nicotinic acid would be sufficient to cause flushing. In any case, the studies show skin benefits of niacinamide whereas skin benefits of nicotinic acid are not well studied. So it is best to avoid hydrolysis by keeping pH neutral and not co-applying with acidic or alkaline products.

Indeed, acid environment may cause some degree of niacinamide hydrolysis. However, it is hard to say w/o a test whether the rate of production and penetration of the resulting nicotinic acid would be sufficient to cause flushing. In any case, the studies show skin benefits of niacinamide whereas skin benefits of nicotinic acid are not well studied. So it is best to avoid hydrolysis by keeping pH neutral and not co-applying with acidic or alkaline products.

Dr. T., one more question, if you please?

In your above comment, you say alkaline products also, should not be co-applied with niacinamide.

How does alkalinity affect niacinamide? What is the reaction that takes place between niacinamide in an alkaline mix?